Loading mechanism and control circuit therefor



March 8, 1960 A. D. F. MoNcRlEFF LOADING MECHANISM AND CONTROL CIRCUIT THEREFOR Filed NOV. 2l. 1955 3 Sheets-Sheet 1 INVENTOR.

A. F. IMONCRIEFF LOADING MECHANISM AND CONTROL CIRCUIT THEREFOR Filed Nov. 2l. 1955 March 8, 1960 3 Sheets-Sheet 2 March 8, 1960 A. D. F. MoNcRlEFF 2,927,509

LOADING MECHANISM AND CONTROL CIRCUIT THEREFOR M 4I-fl "TH 63:1 @AL gebt/E4.

v i aF/vzxsy y punit LOADING MECHANSM AND CGNTROL CRCUH THEREFR Alexander D. F. Moncrie, Bioomheld Hiils, Mich., as-

signor to Michigan Tool Qompany, Detroit, Mich., a corporation of Delaware Application November 21, 1955, Serial No. 547,919

12 Claims. (Cl. 90-4) This invention relates to loading mechanisms for gear bobbing machines and the like and, more particularly, to an improved loading mechanism for automatically loading gear bobbing machines and an improved electrical control system therefor.

An object of the invention is to provide a loading mechanism for gear bobbing machines incorporating improved means for automatically moving gear workpieces into contact with the hob.

Another object of the invention is to provide an improved loading mechanism for gear bobbing machines incorporating improved means for holding and transferring gear workpieces to a machining station.

Another object of the invention is to provide an irnproved loading mechanism for gear hobbing machines which increases the eliieiency and output rate of gear rates Patent is provided with a slide way 30 upon which a slide membobbing machines and reduces the labor incident to the bobbing of gear workpieces.

Another object of the invention is to provide an improved electrical system for controlling the loading and operation of gear bobbing machines.

Still another object ofthe invention is to provide an improved loading mechanism and an improved control system which may be economically manufactured, assembled and installed on a gear bobbing machine.

The above as wel-l as other objects and advantages of the present invention will become apparent fromthe following description, the appended claims and the accompanying drawings wherein:

Figure l is a side elevational view of one embodimentv of the invention, showing the same in installed relationship with respect to a fragmentarily illustrated gear hobbing machine;

Fig. 2 is a fragmentary top plan view of the loading mechanism illustrated in Figure l;

Fig. 3 is a transverse sectional view of a portion of the structure illustrated in Fig. l, taken on the line 3--3 thereof; and

Fig. 4 is a schematic diagram of an electrical control system embodying the present invention.

Referring to the drawings and, more particularly, to Figs. 1-3 thereof, a fragmentarily illustrated gear hobbing machine, generally designated l0, is shown. Gear bobbing machines of the type illustrated include a base l2, a bob spindle housing i4 and a hob support member 16. A rotatable hob spindle i8 is provided which is journaled for rotation in the'housing 14 and which car ries a hob arbor 2b. The arbor 2l) carries a toothed hob 22 which is rotated in contact with a gear blank 24 as will be understood by those skilled in the art. The hobbing machine also includes a retractable tailstock 23 and a headstock 25 which support the gear blank 27 during 'the bobbing thereof.

In accordance with the present invention, a loading mechanism, generally designated 26, is provided which is adapted to feed gear blanks to the hob 22. The loading mechanism 26 includes a support member 28 which is fixed to the base 12 of the bobbing machine and which machine, the. hob. shifter,

ber 32l is mounted for reciprocation, suitable guide members 34 and 36 being lixed to the support member 28 on opposite sides of the slide member 32 to insure the retention of the workpieces in the slide member during movement thereof. The slide member 32 defines a pas# sageway 38 which is open at each end. In cross section, the passageway 38 subtends an arc of more than 180 degrees and is open at .the forward end of the slide member 32 so that a portion of the periphery of a gear blank disposed in the passageway 38 projects outwardly from the slide member and may be moved into contact with the hob 22. However, since in cross section the passageway 38 subtends an arc of more than 180 degrees,

the walls of the passageway 38 contact more than one-v balf of the periphery of the gear blank with the result that the workpiece is returned by the slide member during the bobbing operation, -suiiicient clearance being providedl between tbe workpiece and the slide member to permit the workpiece to rotate in tbe passageway 38. Movement of the workpiece into and out of the slide member is elected by axial movement of the workpiece along the passageway 38.

As shown in Figs. 1 and 2, the slide member 32 is secured to a piston rod 40 of a iiuid actuated piston and cylinder unit 42, as by nuts 44 and 46, the piston and cylinder unit 42 being lixed to the support member 28, as at 48.` As will be described hereinafter in greater detail, the slide member 32 actuates limit switches lLS andl 2LS which are included in the control circuit illustratedtin Fig. '4. g

As shown in Figs. 1 and 2, workpieces are inserted into the passageway 38 of the slide member 32 by means of a fluid actuated piston and cylinder unit 50 having a piston rod 52 secured to a transfer element 54. The transfer element 54 is adapted to engagea workpiece in the lower end of a chute 56.and push the workpiece into the passageway 38, the entering workpiece ejecting the preceding finished workpiece so that the finished workpiece falls into a vchute 58 which conveys the finished workpiece to a suitable receptacle. The piston and cylinder unit actuates a limit switch 3LS which is included in the circuit illustrated in Fig. 4.

Workpieces are supplied to the chute 56 from a con` ventional vibratory feeder unit 60, and the workpieces roll down the chute S6 to the transfer station 62 at the lower end of the chute so that the lowerrnost workpiece is aligned with the passageway 38 in the slide member 32 when the slide member isfin the retracted position,-

vIn the embodiment of the invention illustrated, alimit switch 11LS is engaged by the workpieces in the chute 56 to control the operation of the unit' 60 and the level of the workpieces in the chute. When the level of the gear workpieces in the chute is below the level of the limit switchv 11LS, the limit switch llLS effects the energization of the vibratory unit 60 for an interval of time suiiicierit to refill thechute, as will :be described here` inafter in greater detail. If desired, a conventional photoe-lectric cell 64 may be used in place of or in conjunction with the limit switch 11LSto control the energiza- .for the bobbing machine, an hydraulic motor driven pump 72 for rsupplying tiuid under pressure to the tailstock, the in-feed and side-feed yunits of the bobbing and the transfer and loading battenti-:d Mar. 8, 1960k slides of the loading mechanism. In addition, a coolant pump 74 is provided. The motors 70, 72 and 74 are providedwith conventional magnetic starters M, H and C having contacts M1, HI and C1` interposed between the motors 70,72 and 74, respectively, and the conductors LI, L2 and L3. A transformer 76 is provided which is electrically connected to the conductors L1 and L2, the secondary winding of the transformer being grounded, as at 78, if desired. l

Closure of a start switch 80 energizes the hydraulic pump motor magnetic starter H, the starter H locking in through the'elosure of auxiliary contacts HA so that the hydraulic pump motor 72 will operate continuously until the stop switch 82 is opened, the overload devices H.O.L., M.O.L. or C.O.L. open, or a voltage failure over-travel of the hobber cross-feed slide or some other operational abnormality occurs, the over-travel of the hobber cross-feed opening a limit switch IOLS. The entire control system is thus energized with the magnetic starter H so that all motion is'terminated when the starter H is de-energized. A coolant selector switch 84 is provided which, when closed, en'ergizes the coolant motor magnetic starter C. The energization of the coolant motor starter C is also controlled by a limit switch SLS, as will be described hereinafter in greater detail.

A run-stop selector switch 86 is also provided which, when opened, will terminate a cycle after ejection of the finished workpiece and, when closed, will initiate a cycle or cause one to be repeated. The circuit 66 also includes a return switch 88, which, when opened, will interrupt a cycle at any point and cause it to reverse in sequence. A normal cycle will then follow in the absence of any other operator action.

Assuming that a workpiece is disposed in the passageway 38 in the slide member 32 and that the slide member 32 is retracted, the closure of the start switch 80 will energize a control relay 2CR through the closed contacts SLSA of the limit switch SLS, the limit switch 3LS, the switch 88, and the contacts ITRA of a timer relay ITR. When the relay 2CR is energized, thenormally closed contacts 2CRA thereto open to de-energize a crossfeed return solenoid valve 6SV, the normally closed contacts 2CRB open to de-energize a slide member return solenoid valve SSV, the contacts 2CRC close to energize the slide member 32 advance solenoid valve 7SV, and the normally open contacts ZCRF close to lock in the relay 2CR in a circuit paralleling the limit switch 3LS and the contacts SLSA and connecting the relay 2CR in series with a limit switch 9LS which is engaged when the crossfeed is fully advanced. At this time, the slide member 32 begins to move toward the hob 22. Motion of the slide member 32 rst disengages the limit switch 2LS which opens to de-energize the transfer member 54 forvward solenoid valve 9SV. Near the end of its advancing travel, the slide member 32 effects the engagement of the limit switch ILS which closes to energize the transfer member return solenoid valve 10SV and the control relay ICR, the control relay ICR being provided with contactsICRA which lock in the relay lCR.

The normally open contacts ICRB of the relay ICR then close to energize the tailstock in solenoid valve ISV, vand the normally open contacts ICRC of the relay ICR close to energize a timer relay ITR. Simultaneously, the contacts ICRD of the relay ICR open to de-energize the tailstock out solenoid valve ZSV and the normally open contacts ICRE close to enable the subsequent energization of the coolant motor starter C and main drive motor starter M. The tailstock of the bobbing machine then begins to move in to engage the workpiece. When the tailstock center is fully seated, the tailstock engages the limit switch SLS and the contacts SLSA open to deenergize the timer relay ITR. In the event the delayed opening contacts ITRA of the timer relay ITR open before the limit switch SLS is engaged due to the failure of the tailstock center. to properly seat inthe workpiece,

the relay 2CR is de-energized by the opening of the contacts ITRA. When the relay 2CR is de-energized, the contacts ZCRC open to de-energize the control relay ICR and the slide member advance solenoid valve 7SV. The contacts ICRB of the relay ICR also open to de-energize the tailstock in solenoid valve ISV and the contacts ICRD close to energize the tailstock out solenoid valve ZSV. The contacts 2CRB also close to energize the slide member return solenoid valve SSV and the transfer slide forward solenoid valve 98V. The tailstock then retracts, the slide member 32 retracts and the transfer member moves forwardly to eject the workpiece from the passageway 38 and insert the next workpiece.

When the tailstock center is properly seated in the workpiece, the contacts SLSB of the limit switch close and the contacts SLSA open to de-energize the timer relay ITR. The coolant motor starter C and the drive motor starter -M are energized through closure of the contacts SLSB of the limit switch SLS. The hob infeed solenoid valve 3SV is energized through closure of auxiliary starter contacts MA of the starter M and contacts ZCRD of the relay 2CR. The hob drive motor 70, the coolant motor 74 and the hob infeed unit are then actuated so that the hob is rotated in contact with the workpiece and simultaneously fed into the workpiece. When the full depth of cut is reached, the limit switch 7LS is engaged by the infeed slide of the hobbing rnachine causing the contacts of the limit switch 7LS to close and energize the side-feed advance solenoid valve SSV. The side-feed unit of the bobbing machine then operates to side-feed the hob. At the completion of the side-feed, the gear is then fully hobbed.

At the limit of the side-feed the limit switch 9LS is engaged and opens to de-energize the control relay ZCR. The contacts ZCRD of the relay 2CR then open to deenergize the solenoid valve 3SV the contacts ZCRC open to de-energize the solenoid valves 7SV and 105V and the relay ICR, and the contacts 2VCRE close to energize the hob feed-out solenoid valve 4SV. De-energization of the relay ICR opens the contacts ICRB to de-energize the tailstock in solenoid valve ISV and opens the contacts ICRE to de-energize the coolant starter C and the drive motor starter M. The starter M, in turn, de-energizes the close feed advance solenoid valve SSV through the opening of the auxiliary contacts MA.

At the completion of the hob feed out motion, the limit switch SLS is Vengaged closing contacts SLSA to energize the side feed return solenoid valve 68V and thertailstock out solenoid valve 25V. When the tailstock center disengages from the workpiece, the contacts SLSB of the limit switch SLS open and deenergize the hob feed out solenoid valve 4SV, and when the tailstock of the bobbing machine is fully retracted, the limit switch 6LS is closed to energize the slide member 32 return solenoid valve SSV. When the slide member 32 is retracted, the limit switch 2LS is closed to energize the transfer member forward solenoid valve V. The transfer member 54 then inserts a new workpiece into the passageway 38 and ejects the nished gear from the passageway 38. At the limit of its travel, the transfer member 54 engages the limit switch 3LS to again energize the relay ZCR. l The relay 2CR then de-energizes the solenoid valve 65V through the opening of the contacts 2CRA, and the solenoid valves SSV and 98V through the opening of the contacts 2CRB, thereby completing the cycle. AIf the switch 86 is closed, the slide member advance solenoid valve 7SV is energized and the cycle repeats.

After each bobbing cycle, the hob shifter of the bobbing machine is successively advanced to utilize the full face of the hob. When the hob shifter reaches the limit of its travel so that the full hob face has been utilized, the limit switch 4LS is engaged so that the contacts 4LSA close to energize a warning lamp R and the .contacts 4LSB open to `cle-energize the tailstock in sole,-

noid valve ESV. The operator then reverses the vhob shifter and inspects the hob. Return of the hob shifter restores the limit switch 4LS to its initial position shown in Fig. 4, thereby extinguishing the warning light R and rte-establishing the circuit through the tailstock in solenoid valve lSV.

When the level of the gear workpieces in the feed chute 56 falls below the level of the limit switch lLS, the limit switch MLS is closed to energize timer relays ZTR and STR. The timer relay ZTR is set for a-time interval or" operation for the vibratory feeder Gti so as to maintain the feeder 60 energized for a time after the limit switch llLS is engaged by the workpieces and opened. The timer relay STR is set for a longer period of feeder operation and in the event the timer relay STR times out before the timer relay ZTR, the relay SCR is energized. When the timer relay 2TR is energized, the contacts 2TRA close to energize the vibratory feeder 60, and when the relay ZTR is de-energized, the contacts :ETR open after a short interval to de-energize the feeder 6i?. lf the relay SCR is energized by closure of the contacts STRA of the timer relay STR, the relay SCR will lock itself in through closure of the contacts BCRA, thereby energizing a warning lamp Rl and de-energizing the control relay lCR by opening the'contacts SCRB of the relay SCR. The opening of the contacts SCRB in-v terrupts the cycle after ejection of the workpiece. After the unit 6l) has been relled or any obstructions removed which prevented the filling of the chute 56, the relay SCR may be de-energized by opening the switch S2 to de-energize the control circuit and then closing the switch 86 to re-energize the timer relays 3TR and 2'l`R. The vibratory feeder will then operate and upon the opening of the contacts 2TRA will be de-energized in the manner described hereinabove, the opening of the limit switch MLS de-energizing the timer relays STR and ZTR.

Manual operation of the hobber can be elfected by closing the contacts 90A and 90C Vand opening the contacts 90B and 90D of a switch 9d. ln this position, tae contacts tBA are closed to energize the relay lCR, the contacts 99B are open so as to de-energize the photoelectriccell 64, if such cell is used, the contacts 90C are closed to bridge the limit switch SLS to permit the direct energization of the control relay ZCR and the con tacts 90D are open to open the circuit through the switch 86 and the contacts SCRB of the relay 3CR. The switch 83 is then opened to de energize the relay ZCR and energize the slide member return solenoid valve SSV. The transfer return solenoid lvalve ltlSV is then energized by the closure of the contacts lC'RA after the relay CR is energized and locked in by the closure of a switch 92. At this time, the slide member and the transfer element will remain inoperative. After a workpiece is manually loaded into the passageway 38, the switch 92 is closed to energize the relay lCR and the hobbing cycle progresses as described above. The cycle ends with the side-feed slide of the hobbing machine returned, the hobbing feed unit out, and the tailstock withdrawn. When the switch 94 is set in the manual position so as to open the contacts 94A, 94B and 94D and close the contacts 94C and 94E, the tailStock can only be operated by opening and closing the switch 96. With the switch 96 in the position shown in Fig. 4, the tailstock is withdrawn at the end of the hobbing cycle.

While a preferred embodiment of the invention has been shown and described, it will understood that various changes and modifications may be made without departing from the spirit of the invention.

What is claimed is:

l. In a loading mechanism for gear hobbing machines and the like having workpiece supporting means, the combination comprising a slide way, a slide member mounted on said slide way for reciprocating movement relative to said supporting means and defining a recess adapted to receive a portion of a workpiece, means for inserting recess for actuating said reciprocating means toward itsretracted position.

2. In a loading mechanism for gear hobbing machines and the like having a workpiece supporting element, the

Ycombination comprising a loading member deiining a recess open at each end and adapted to receive a workpiece whereby at least a portionl of the periphery of the workpiece terminates in outwardly spaced relationship with respect to the loading member, means for successively inserting workpieces into said recess, means for moving said loading member toward and away from said supporting element, and means for retracting said loading member from said supporting element upon the failure of a workpiece in said recess to engage said supporting element.

3. ln combination with a gear hobbing machine having workpiece supporting means, a loading mechanism comprising a slide member delining a recess adapted to receive a workpiece whereby at least a portion. of the ,eriphery of the workpiece terminates in outwardly spaced relationship with respect to said slide member, means for successively feeding `workpieces to said slide member, means for moving said slide member toward and away from said supporting means, and means actuated by said supporting means for actuating said slide member away from said supporting means upon failure of said supporting .means to engage a workpiece in said recess.

4. ln combination with a gear hobbing machine having a workpiece supporting element, a loading mechanism including a slide member dening a recess, said slide member being mounted for movement toward and away .from said supporting element, said slide member being adapted to support a workpiece whereby at least a-portion of the periphery of the workpiece terminates in outwardly spaced relationship with respect to the slide member, transfer means for successively feeding workpieces to said slide member, and means actuated by said supporting element for successively actuating said slide member away from said supporting element and saidl transfer means to'feed another workpiece to said slide member upon failure of saidsupportingelement to engage aworkpiece in said recess.

5. In combination with a gear hobbing machine haw ling a workpiece supporting element, a loading mechanism including a slide member dening a recess, said slide member being mounted for movement toward and away from said supporting element, said slide member being adapted to support a workpiece whereby at least a portion of the periphery of the workpiece terminates in outwardly spaced relationship with respect to the slide member, transfer means for successively feeding work pieces to said slide member, and electroresponsive means actuated by said supporting element for actuating said slide member away from said supporting element and said transfer means to feed another workpiece to said slide member upon failure of said supporting element to engage a workpiece in said recess.

6. In combination with a gear finishing machine having a workpiece supporting element, a loading mechanism including a slide member defining a recess open at the forward end thereof, said slide member being mounted for reciprocating movement toward and away from said supporting element, transfer means for successively inserting workpieces into said recess, means for moving said slide member toward and away from said supporting element, and means including relay means operable upon the failure of said supporting element to engage a workpiece in said recess for actuating said slide member away from said supporting element and said '7 transfer means to insert another workpiece into said recess.y

l7. In combination with a gear bobbing machine having a reciprocable workpiece supporting element, loading means for successively moving gear workpieces into contact with said element, an electrical control system operatively connected to said machine and to said loading means, said control system being eiective to actuate said supporting element and said loading means, and means in said control system effective to retract saidy support clement and said loading means upon failure of' a gear workpiece to engage said element.

8. in combination with a gear hobbing machine having a reciprocable supporting element, a slide member adapted to releasabiy retain a gear workpiece and move the gear workpiece into contact with said supporting element, actuating means operatively connected to said slide member for advancing said slide member toward said supporting element, and an electric network including switch means responsive to the movement of said supporting element in a predetermined direction relative to said slide member for controlling said actuating means to effect movement of said slide member.

9. In an electrical control system for controlling a gear producing machine having a workpiece supporting means and a slide member mounted for reciprocating movement toward and away from said workpiece supporting means and adapted to releasably retain a gear workpiece, a source of electrical potential, a first circuit arranged to be energized from said source and effective to control movementV of said slide member, a second electrical circuit arranged to be energized from said source, electrical switch means in said second circuit actuable upon the failure of said supporting means t seat against a workpiece and controlling energy ow through said second circuit, and means including electrovresponsive means in said second circuit controlling the energization of said first circuit.

10. In an electrical control system for controlling a gear producing machine having a workpiece supporting means and a slide member mounted for reciprocating movement toward and away from said workpiece supporting means and adapted to releasably retain a gear workpiece, a source of electrical potential, a first circuit arranged to be energized from said source and effective to controi movement of said slide member, a second electrical circuit arranged to be energized from said source, electrical time delay switch means in said second circuit Y 'actuable upon the failure of said support means to seat against a workpiece and controlling energy liowthrough said second circuit, and means including electroresponsive means in said second circuit controlling the energization of said rst circuit.

11. In an electrical control system for controlling a gear producing machine having workpiece supporting means and a slide member mounted for reciprocating movement toward and away from said workpiece supporting means and adapted to releasably retain a gear workpiece, a source ofelectricalpotential, a rst circuit arranged to be energizedirom said source and eiective to control movement'of said slide member, a second electrical circuitY arranged to be energized from said source, electrical time delay switch means in said second circuit actuable upon the failure of said support means to seat against a workpiece and controlling energy iiow through Y said second circuit, current ow responsive means associated with said second circuit and responsive to current flow in said second circuit, and means including a pair of contacts in said first circuit controlled by said current flow responsive means for controlling the energization of said rst circuit.

12. in an electrical control system for controlling a gear producing machine having workpiece supporting means and a slide member mounted for reciprocating movement toward and away from said workpiece supporting means and adapted to releasably retain a gear workpiece, a source of electrical potential, a first circuit arranged to be energized from said source and eective to control movement of said yslide member, a second electrical circuit arranged to be energized from said source, electric time delay switch means in said second circuit actuable upon` the failure of said support means to seat against a workpiece and controlling energy ow through said second circuit, and means including relay means in said second circuit responsive to current ow in. said second circuit for controlling the energization of said rst circuit.

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